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20efb856e1
Multipath TCP (MPTCP), standardized in RFC8684 [1], is a TCP extension
that enables a TCP connection to use different paths.
Multipath TCP has been used for several use cases. On smartphones, MPTCP
enables seamless handovers between cellular and Wi-Fi networks while
preserving established connections. This use-case is what pushed Apple
to use MPTCP since 2013 in multiple applications [2]. On dual-stack
hosts, Multipath TCP enables the TCP connection to automatically use the
best performing path, either IPv4 or IPv6. If one path fails, MPTCP
automatically uses the other path.
To benefit from MPTCP, both the client and the server have to support
it. Multipath TCP is a backward-compatible TCP extension that is enabled
by default on recent Linux distributions (Debian, Ubuntu, Redhat, ...).
Multipath TCP is included in the Linux kernel since version 5.6 [3]. To
use it on Linux, an application must explicitly enable it when creating
the socket. No need to change anything else in the application.
This attached patch adds MPTCP per address support, to be used with:
mptcp{,4,6}@<address>[:port1[-port2]]
MPTCP v4 and v6 protocols have been added: they are mainly a copy of the
TCP ones, with small differences: names, proto, and receivers lists.
These protocols are stored in __protocol_by_family, as an alternative to
TCP, similar to what has been done with QUIC. By doing that, the size of
__protocol_by_family has not been increased, and it behaves like TCP.
MPTCP is both supported for the frontend and backend sides.
Also added an example of configuration using mptcp along with a backend
allowing to experiment with it.
Note that this is a re-implementation of Björn's work from 3 years ago
[4], when haproxy's internals were probably less ready to deal with
this, causing his work to be left pending for a while.
Currently, the TCP_MAXSEG socket option doesn't seem to be supported
with MPTCP [5]. This results in a warning when trying to set the MSS of
sockets in proto_tcp:tcp_bind_listener.
This can be resolved by adding two new variables:
sock_inet(6)_mptcp_maxseg_default that will hold the default
value of the TCP_MAXSEG option. Note that for the moment, this
will always be -1 as the option isn't supported. However, in the
future, when the support for this option will be added, it should
contain the correct value for the MSS, allowing to correctly
set the TCP_MAXSEG option.
Link: https://www.rfc-editor.org/rfc/rfc8684.html [1]
Link: https://www.tessares.net/apples-mptcp-story-so-far/ [2]
Link: https://www.mptcp.dev [3]
Link: https://github.com/haproxy/haproxy/issues/1028 [4]
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/515 [5]
Co-authored-by: Dorian Craps <dorian.craps@student.vinci.be>
Co-authored-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
58 lines
2.0 KiB
C
58 lines
2.0 KiB
C
/*
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* include/haproxy/sock_inet.h
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* This file contains declarations for AF_INET & AF_INET6 sockets.
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*
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* Copyright (C) 2000-2020 Willy Tarreau - w@1wt.eu
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _HAPROXY_SOCK_INET_H
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#define _HAPROXY_SOCK_INET_H
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <haproxy/api.h>
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extern int sock_inet6_v6only_default;
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extern int sock_inet_tcp_maxseg_default;
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extern int sock_inet6_tcp_maxseg_default;
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#ifdef HA_HAVE_MPTCP
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extern int sock_inet_mptcp_maxseg_default;
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extern int sock_inet6_mptcp_maxseg_default;
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#else
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#define sock_inet_mptcp_maxseg_default -1
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#define sock_inet6_mptcp_maxseg_default -1
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#endif
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extern struct proto_fam proto_fam_inet4;
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extern struct proto_fam proto_fam_inet6;
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/* external types */
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struct receiver;
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int sock_inet4_addrcmp(const struct sockaddr_storage *a, const struct sockaddr_storage *b);
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int sock_inet6_addrcmp(const struct sockaddr_storage *a, const struct sockaddr_storage *b);
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void sock_inet_set_port(struct sockaddr_storage *addr, int port);
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int sock_inet_get_dst(int fd, struct sockaddr *sa, socklen_t salen, int dir);
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int sock_inet_is_foreign(int fd, sa_family_t family);
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int sock_inet4_make_foreign(int fd);
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int sock_inet6_make_foreign(int fd);
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int sock_inet_bind_receiver(struct receiver *rx, char **errmsg);
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#endif /* _HAPROXY_SOCK_INET_H */
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